Virtual reality simulator and virtual reality simulation program

ABSTRACT

A VR (Virtual Reality) simulator projects or displays a virtual space image on a screen installed at a position distant from a user in a real space and not integrally moving with the user. More specifically, the VR simulator acquires a real user position being a position of the user&#39;s head in the real space. The VR simulator acquires a virtual user position being a position in a virtual space corresponding to the real user position. Then, the VR simulator acquires the virtual space image by imaging the virtual space by using a camera placed at the virtual user position in the virtual space, based on virtual space configuration information indicating a configuration of the virtual space. Here, the VR simulator performs a lens shift process that shifts a lens of the camera such that the entire screen fits within a field of view of the camera.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2021-115014 filed on Jul. 12, 2021, the entire contents of which areincorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to a virtual reality (VR) simulation. Inparticular, the present disclosure relates to a wearless VR simulation.

Background Art

Patent Literature 1 discloses an image display device. The image displaydevice includes an image generation unit, a projector, and a detectionunit. The image generation unit uses data of a space of a virtual worldto generate an image of a part of the virtual world captured by avirtual camera set in the space of the virtual world. The projectormoves integrally with a user and projects the image generated by theimage generation unit onto a space of a real world. The detection unitdetects a position of the projector and a projecting direction of theprojector. The image generation unit moves the virtual camera in thespace of the virtual world in conjunction with the movement of theprojector. Moreover, the image generation unit sets the virtual camerasuch that its imaging direction becomes a direction corresponding to theprojecting direction of the projector. When a direction of the userchanges and thus the projecting direction of the projector changes, theimaging direction of the virtual camera also changes accordingly.

Patent Literature 2, Patent Literature 3, and Patent Literature 4 areother examples indicating a technical level in a technical field of thepresent disclosure at the time of application.

LIST OF RELATED ART

-   Patent Literature 1: Japanese Laid-Open Patent Publication No.    JP-2018-056924-   Patent Literature 2: Japanese Laid-Open Patent Publication No.    JP-2003-141573-   Patent Literature 3: Japanese Laid-Open Patent Publication No.    JP-2004-110804-   Patent Literature 4: Japanese Patent No. 3761563

SUMMARY

A “wearless VR simulation” where a user is able to experience the VRwithout wearing a VR device such as a head-mounted display isconsidered. In the case of the wearless VR simulation, a screen isinstalled at a position distant from the user, and an image of a virtualworld (virtual space) is drawn on the screen. In such the wearless VRsimulation, it is desirable to suppress the user's feeling ofstrangeness as possible.

An object of the present disclosure is to provide a technique that cansuppress the user's feeling of strangeness in the wearless VRsimulation.

A first aspect is directed to a virtual reality simulator.

The virtual reality simulator includes:

one or more processors; and

one or more memory devices storing virtual space configurationinformation indicating a configuration of a virtual space.

The one or more processors are configured to execute:

a process of acquiring information on a real user position that is aposition of a head of a user in a real space;

a process of acquiring information on a virtual user position that is aposition in the virtual space corresponding to the real user position;

an imaging process that acquires a virtual space image by imaging thevirtual space by using a camera placed at the virtual user position inthe virtual space, based on the virtual space configuration information;and

a process of projecting or displaying the virtual space image on ascreen that is installed at a position distant from the user in the realspace and does not integrally move with the user.

The imaging process includes a lens shift process that shifts a lens ofthe camera such that whole of the screen fits within a field of view ofthe camera.

A second aspect further includes the following feature in addition tothe first aspect.

The imaging process further includes a perspective adjustment processthat adjusts a focal length of the camera such that perspectivecorresponding to a distance between the real user position and thescreen is cancelled.

A third aspect further includes the following feature in addition to thefirst or second aspect.

The one or more processors predict the real user position in futurebased on a past history of the real user position.

Then, the one or more processors execute the imaging process based onthe virtual user position in future corresponding to the real userposition in future.

A fourth aspect is directed to a virtual reality simulation programexecuted by a computer and performing a virtual reality simulation.

The virtual reality simulation program causes the computer to execute:

a process of acquiring information on a real user position that is aposition of a head of a user in a real space;

a process of acquiring information on a virtual user position that is aposition in a virtual space corresponding to the real user position;

an imaging process that acquires a virtual space image by imaging thevirtual space by using a camera placed at the virtual user position inthe virtual space, based on virtual space configuration informationindicating a configuration of the virtual space; and

a process of projecting or displaying the virtual space image on ascreen that is installed at a position distant from the user in the realspace and does not integrally move with the user.

The imaging process includes a lens shift process that shifts a lens ofthe camera such that whole of the screen fits within a field of view ofthe camera.

According to the present disclosure, it is possible to suppress theuser's feeling of strangeness in the wearless VR simulation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram for explaining an outline of a wearlessVR simulation according to an embodiment of the present disclosure;

FIG. 2 is a conceptual diagram for explaining an outline of a wearlessVR simulation according to an embodiment of the present disclosure;

FIG. 3 is a block diagram showing a configuration example of a VRsimulator according to an embodiment of the present disclosure;

FIG. 4 is a block diagram showing a functional configuration example ofa VR simulator according to an embodiment of the present disclosure;

FIG. 5 is a flow chart showing processing by a VR simulator according toan embodiment of the present disclosure;

FIG. 6 is a conceptual diagram for explaining a virtual space imagingprocess (Step S130) according to an embodiment of the presentdisclosure;

FIG. 7 is a conceptual diagram for explaining a first feature of avirtual space imaging process (Step S130) according to an embodiment ofthe present disclosure;

FIG. 8 is a conceptual diagram for explaining a second feature of avirtual space imaging process (Step S130) according to an embodiment ofthe present disclosure;

FIG. 9 is a conceptual diagram for explaining a third feature of avirtual space imaging process (Step S130) according to an embodiment ofthe present disclosure; and

FIG. 10 is a block diagram for explaining a modification example of anembodiment of the present disclosure.

EMBODIMENTS

Embodiments of the present disclosure will be descried with reference tothe attached drawings.

1. Outline of Wearless VR Simulation

FIG. 1 is a conceptual diagram for explaining an outline of a wearlessVR (Virtual Reality) simulation according to the present embodiment. Inthe wearless VR simulation, a user 1 is able to experience the VRwithout wearing a VR device such as a head-mounted display.

More specifically, at least one screen 4 is installed at a positiondistant from the user 1. Unlike the head-mounted display, the screen 4is independent of the user 1 and does not move integrally with the user1. A position of the screen 4 may be fixed. The screen 4 may beinstalled vertically on the ground. A plurality of screens 4 may beinstalled around the user 1. The plurality of screens 4 may beseamlessly and continuously arranged. In the example shown in FIG. 1 , aplurality of screens 4 are installed vertically on the ground andarranged seamlessly and continuously so as to be orthogonal to eachother. The screen 4 may be larger than the user 1. The screen 4 isinstalled, for example, in a VR experience room.

An image of a virtual world (virtual space) is drawn on such the screen4 distant from the user 1. For example, a projector is installed at aposition away from the screen 4, and the image is projected from theprojector onto the screen 4. As another example, the screen 4 may be ascreen of a display device such as a liquid crystal display, an organicEL display, and the like. In that case, the image is displayed on thescreen 4 of the display device. In the following description, “drawingan image on the screen 4” means projecting or displaying an image on thescreen 4.

In the wearless VR simulation described above, it is desirable tosuppress the user 1's feeling of strangeness as possible. For example,there is an object OBJ in the virtual world. It is desirable to draw theobject OBJ on the screen 4 such that the object OBJ can be seen from aposition of the user 1 without the feeling of strangeness. The feelingof strangeness being little means, for example, that distortion of theimage of the object OBJ drawn on the screen 4 is little. As anotherexample, the feeling of strangeness being little means that a sense ofdistance of the object OBJ drawn on the screen 4 is close to reality. Aswill be described later, the present embodiment provides a techniquethat can suppress the user 1's feeling of strangeness in the wearless VRsimulation.

Major terms used in the present embodiment will be described withreference to FIG. 2 .

A “real space SPr” is a space in which the user 1 and the screen 4actually exist. In the real space SPr, at least one screen 4 isinstalled away from the user 1.

A “real space coordinate system (Xr, Yr, Zr)” is a coordinate systemthat defines the real space SPr. An origin of the real space coordinatesystem is set at an arbitrary position in the real space SPr. A Xr-axis,a Yr-axis, and a Zr-axis are orthogonal to each other. The Xr-axis andthe Yr-axis represent horizontal directions, and the Zr-axis representsa vertical direction.

A “real user position Ur” is a position of user 1 in the real space SPr(i.e., the real space coordinate system). More specifically, the realuser location Ur is a position of a head of the user 1 in the real spaceSPr. For example, the real user position Ur is a position of an eye ofthe user 1 in the real space SPr. The real user position Ur may be acenter position of both eyes of the user 1 in the real space SPr.

A “virtual space SPv” is a space of a virtual world that is a target ofthe VR simulation. The virtual world is arbitrary. For example, thevirtual world is a city. As another example, the virtual world may be aworld of a game.

A “virtual space coordinate system (Xv, Yv, Zv)” is a coordinate systemthat defines the virtual space SPv. An origin of the virtual spacecoordinate system is set at an arbitrary position in the virtual spaceSPv. A Xv-axis, a Yv-axis, and a Zv-axis are orthogonal to each other.The Xv-axis and the Yv-axis represent horizontal directions, and theZv-axis represents a vertical direction.

A “virtual user position Uv” is a position of user 1 in the virtualspace SPv (i.e., the virtual space coordinate system).

The real space coordinate system (Xr, Yr, Zr) and virtual spacecoordinate system (Xv, Yv, Zv) are associated with each other inadvance. Therefore, coordinate transformation between the real spacecoordinate system and the virtual space coordinate system is possible.That is, it is possible to convert any position in the real spacecoordinate system into a corresponding position in the virtual spacecoordinate system. Conversely, it is also possible to convert anyposition in the virtual space coordinate system into a correspondingposition in the real space coordinate system. For example, it ispossible to convert the real user position Ur into a correspondingvirtual user position Uv. As another example, it is possible to convertthe position of the screen 4 in the real space SPr into a correspondingposition in the virtual space SPv. As yet another example, it is alsopossible to convert a position of the object OBJ in the virtual spaceSPv into a corresponding position in the real space SPr.

A “VR simulator 10” is a simulator that achieves the wearless VRsimulation according to the present embodiment. The VR simulator 10 ispresent in the real space SPr. Hereinafter, the VR simulator 10according to the present embodiment will be described in detail.

2. VR Simulator 2-1. Configuration Example of VR Simulator

FIG. 3 is a block diagram showing a configuration example of the VRsimulator 10 according to the present embodiment. The VR simulator 10includes a sensor 20, an information processing device 30, and a drawingdevice 40.

The sensor 20 detects information used for acquiring the real userposition Ur. For example, the sensor 20 is a camera that images (i.e.,captures an image of) the user 1. As another example, the sensor 20 maybe a position sensor mounted on the head of the user 1. Various examplesof a method for acquiring the real user position Ur by the use of thesensor 20 will be described in detail later.

The drawing device 40 draws an image on the screen 4. For example, thedrawing device 40 is a projector. The projector is installed at aposition away from the screen 4 and projects an image onto the screen 4.As another example, the drawing device 40 is a display device such as aliquid crystal display, an organic EL display, and the like. The displaydevice is provided with a screen 4 and displays an image on its ownscreen 4.

The information processing device 30 is a computer that executes avariety of information processing. The information processing device 30includes one or more processors 31 (hereinafter, simply referred to as aprocessor 31) and one or more memory devices 32 (hereinafter, simplyreferred to as a memory device 32). The processor 31 executes a varietyof processing. For example, the processor 31 includes a CPU (CentralProcessing Unit). The memory device 32 stores a variety of information.Examples of the memory device 32 include a volatile memory, anon-volatile memory, an HDD (Hard Disk Drive), an SSD (Solid StateDrive), and the like.

A VR simulation program 100 is a computer program that performs thewearless VR simulation. The wearless VR simulation according to thepresent embodiment is achieved by the information processing device 30(the processor 31) executing the VR simulation program 100. The VRsimulation program 100 is stored in the memory device 32. The VRsimulation program 100 may be recorded on a non-transitorycomputer-readable recording medium. The VR simulation program 100 may beprovided via a network.

Coordinate transformation information 210, virtual space configurationinformation 220, and screen information 230 are beforehand stored in thememory device 32.

The coordinate transformation information 210 indicates a correspondencerelationship between the real space coordinate system (Xr, Yr, Zr) andthe virtual space coordinate system (Xv, Yv, Zv) (see FIG. 2 ). Usingthe coordinate transformation information 210 makes it possible toperform the coordinate transformation between the real space coordinatesystem and the virtual space coordinate system.

The virtual space configuration information 220 indicates aconfiguration of the virtual space SPv. More specifically, there are avariety of objects OBJ in the virtual space SPv. The virtual spaceconfiguration information 220 indicates an occupancy range of eachobject OBJ in the virtual space SPv (i.e., in the virtual spacecoordinate system). For example, the virtual space configurationinformation 220 indicates a position, a size, and a shape of each objectOBJ in the virtual space SPv (i.e., in the virtual space coordinatesystem).

The screen information 230 indicates information on each screen 4installed in the real space SPr. More specifically, the screeninformation 230 indicates an occupancy range of each screen 4 in thereal space SPr (i.e., in the real space coordinate system). For example,the screen information 230 indicates a position, a size, and a shape ofeach screen 4 in the real space SPr (i.e., in the real space coordinatesystem).

2-2. Example of Processing by VR Simulator

FIG. 4 is a block diagram showing a functional configuration example ofthe VR simulator 10 according to the present embodiment. The VRsimulator 10 includes a real user position acquisition unit 110, avirtual user position acquisition unit 120, a virtual space imaging unit130, and a drawing unit 140 as functional blocks. These functionalblocks are implemented by a cooperation of the processor 31 executingthe VR simulation program 100 and the memory device 32.

FIG. 5 is a flow chart showing processing by the VR simulator 10according to the present embodiment. A process flow by the VR simulator10 will be described with reference to FIGS. 4 and 5 .

2-2-1. Step S110 (Real User Position Acquisition Process)

In Step S110, the real user position acquisition unit 110 acquires thereal user position Ur in the real space SPr. As described above, thereal user position Ur is the position of the head of the user 1 in thereal space SPr. For example, the real user position Ur is the positionof an eye of the user 1 in the real space SPr. As another example, thereal user position Ur may be a center position of both eyes of the user1 in the real space SPr.

More specifically, the sensor 20 installed in the real space SPr detectsinformation used for acquiring the real user position Ur.Sensor-detected information 200 indicates a result of detection by thesensor 20. The real user position acquisition unit 110 acquires thesensor-detected information 200 from the sensor 20. The sensor-detectedinformation 200 is stored in the memory device 32. Then, the real userposition acquisition unit 110 acquires the real user position Ur basedon the sensor-detected information 200. The information on the real userposition Ur is stored in the memory device 32.

For example, the sensor 20 includes at least one camera that images(captures an image of) the user 1. For example, the camera is installedat a predetermined position in the VR experience room. Information on ainstallation position and a installation direction of the camera in thereal space coordinate system is given in advance. The sensor-detectedinformation 200 is an image of the user 1 captured by the camera. Thereal user position acquisition unit 110 recognizes the head (e.g., eyes)of the user 1 by analyzing the image of the user 1 indicated by thesensor-detected information 200. Then, the real user positionacquisition unit 110 acquires the real user position Ur based on arelative position of the head of the user 1 viewed from the camera, theinstallation position and the installation direction of the camera.

As another example, the sensor 20 may be a position sensor mounted onthe head of the user 1. For example, the position sensor is a rangingsensor that measures relative distances to a wall and a ceiling of theVR experience room. In that case, the sensor-detected information 200 isthe relative distances measured by the position sensor. Information onpositions of the wall and the ceiling in the real space coordinatesystem is given in advance. The real user position acquisition unit 110is able to acquire the real user position Ur based on the positions ofthe wall and the ceiling and the relative distances to them.

2-2-2. Step S120 (Virtual User Position Acquisition Process)

In Step S120, the virtual user position acquisition unit 120 acquiresthe virtual user position Uv corresponding to the real user position Uracquired in Step S110. More specifically, the virtual user positionacquisition unit 120 converts the real user position Ur into acorresponding virtual user position Uv based on the coordinatetransformation information 210. The information on the virtual userposition Uv is stored in the memory device 32.

2-2-3. Step S130 (Virtual Space Imaging Process)

In Step S130, the virtual space imaging unit 130 generates an image ofthe virtual space SPv viewed from the virtual user position Uv, that is,performs rendering. The image of the virtual space SPv viewed from thevirtual user position Uv is hereinafter referred to as a “virtual spaceimage IMG.”

FIG. 6 is a conceptual diagram for explaining Step S130. The virtualspace imaging unit 130 places a virtual camera VC at the virtual userposition Uv in the virtual space SPv. The virtual camera VC is a cameraimplemented by a software. Parameters of the virtual camera VC such as afocal length, a sensor size, and the like are set to be consistent withhuman vision. Then, the virtual space imaging unit 130 images thevirtual space SPv by using the virtual camera VC placed at the virtualuser position Uv. The image of the virtual space SPv captured by thevirtual camera VC is the virtual space image IMG. The configuration ofthe virtual space SPv, that is, the position, the shape, and size ofeach object OBJ in the virtual space SPv (i.e., in the virtual spacecoordinate system) are obtained from the virtual space configurationinformation 220. Therefore, based on the virtual space configurationinformation 220, the virtual space imaging unit 130 is able to acquirethe virtual space image IMG by imaging the virtual space SPv, that is,to perform rendering.

The virtual space imaging unit 130 may acquire the virtual space imageIMG for each screen 4. The position of each screen 4 in the real spaceSPr is obtained from the screen information 230. The virtual spaceimaging unit 130 acquires a position of each screen 4 in the virtualspace SPv based on the screen information 230 and the coordinatetransformation information 210. Then, the virtual space imaging unit 130uses the virtual camera VC to image the virtual space SPv in a directionfrom the virtual user position Uv to each screen 4. Alternatively, thevirtual space imaging unit 130 may image the virtual space SPv inall-around direction from the virtual user position Uv.

It should be noted that in the present embodiment, information on adirection of the user 1's gaze is unnecessary. The virtual camera VCimages the virtual space SPv in a predetermined direction regardless ofthe direction of the user 1's gaze. The predetermined direction includesthe direction from the virtual user position Uv to each screen 4. Thepredetermined direction may be the all-around direction. The virtualspace imaging unit 130 does not crop the virtual space image IMG in thedirection of the user 1's gaze but acquires the virtual space image IMGthat is visible from the virtual user position Uv. As a comparativeexample, according to the technique disclosed in Patent Literature 1described above, an imaging direction of a virtual camera changes inconjunction with a change in a user's direction.

In the virtual space imaging process (Step S130), an ingenuity isexercised in order to suppress the feeling of strangeness when thevirtual space image IMG is drawn on the screen 4. The ingenuity forsuppressing the feeling of strangeness will be described in detail inSection 3 below.

2-2-4. Step S140 (Drawing Process)

In Step S140, the drawing unit 140 controls the drawing device 40 todraw the virtual space image IMG on the screen 4. At this time, thedrawing unit 140 may draw the virtual space image IMG acquired for eachscreen 4 on for each screen 4. When the drawing device 40 is aprojector, the drawing unit 140 controls the projector to project thevirtual space image IMG onto the screen 4. As another example, when thedrawing device 40 is a display device, the drawing unit 140 controls thedisplay device. to display the virtual space image IMG on the screen 4.

3. Features of Virtual Space Imaging Process (Step S130)

In the virtual space imaging process (Step S130), an ingenuity isexercised in order to suppress the feeling of strangeness when thevirtual space image IMG is drawn on the screen 4. Hereinafter, threetypes of processes, “fixation of vanishing point”, “lens shift”, and“perspective adjustment” will be described as features of the virtualspace imaging process according to the present embodiment. The effect ofsuppressing the user 1's feeling of strangeness can be at least obtainedby at least one of the three types of characteristic processes. Ofcourse, two or more of the three types of characteristic processes maybe performed.

3-1. Fixation of Vanishing Point

FIG. 7 is a conceptual diagram for explaining a first feature of thevirtual space imaging process (Step S130). As the first feature, avanishing point of the virtual space image IMG is fixed at a positionstraight in a horizontal direction as viewed from the virtual userposition Uv. In other words, the virtual space imaging unit 130 acquiresthe virtual space image IMG such that the vanishing point exists in thehorizontal direction as viewed from the virtual user position Uv.

Regardless of the direction of the user 1's gaze, the vanishing point isfixed in the horizontal direction as viewed from the virtual userposition Uv. Even when the direction of the user 1's gaze moves up anddown, the virtual camera VC is not rotated up and down. If the virtualcamera VC is rotated up and down in conjunction with the moving up anddown of the direction of the user 1's gaze, vertical lines of thevirtual space image IMG drawn on the screen 4 converge and thus thevirtual space image IMG looks distorted. According to the presentembodiment, the vanishing point is fixed in the horizontal directionregardless of the direction of the user 1's gaze, and thus the virtualspace image IMG drawn on the screen 4 is prevented from being distorted.That is to say, it is possible to suppress the user 1's feeling ofstrangeness.

Of course, when the user 1 moves the gaze in the real space SPr, a fieldof view of the user 1 changes accordingly. At that time, just as anobject itself existing in the real space SPr does not change at all, sothe virtual space image IMG itself drawn on the screen 4 around the user1 does not change at all.

3-2. Lens Shift

FIG. 8 is a conceptual diagram for explaining a second feature of thevirtual space imaging process (Step S130). As the second feature, thevirtual space imaging unit 130 performs a “lens shift process” thatshifts a lens of the virtual camera VC such that whole of the screen 4fits within a field of view of the virtual camera VC. In the lens shiftprocess, the virtual space imaging unit 130 shifts the lens of thevirtual camera VC in the vertical direction and/or the horizontaldirection without changing a focal length. It should be noted that theposition of the vanishing point is not changed by the lens shift.

An amount of lens shift required for fitting the whole of the screen 4within the field of view of the virtual camera VC can be determined fromthe size of the screen 4 and a positional relationship between the realuser position Ur and the screen 4. The position and the size of thescreen 4 in the real space SPr are obtained from the screen information230. Therefore, the virtual space imaging unit 130 is able to determinethe amount of lens shift required for fitting the whole of the screen 4within the field of view of the virtual camera VC, based on the realuser position Ur and the screen information 230.

Performing such the lens shift process suppresses occurrence of an areain the screen 4 with nothing on it. Therefore, the user 1's sense ofimmersion in the VR increases.

Again, what is important here is not to rotate the virtual camera VC upand down. If the virtual camera VC is rotated up and down in order tofit the whole of the screen 4 within the field of view, the verticallines of the virtual space image IMG drawn on the screen 4 converge andthus the virtual space image IMG looks distorted. According to thepresent embodiment, rather than rotating the virtual camera VC up anddown, the lens shift process that shifts the lens of the virtual cameraVC is performed. It is thus possible to prevent the virtual space imageIMG drawn on the screen 4 from being distorted. That is to say, it ispossible to suppress the user 1's feeling of strangeness.

3-3. Adjustment of Perspective

FIG. 9 is a conceptual diagram for explaining a third feature of thevirtual space imaging process (Step S130). An image of an object OBJ isdrawn on a screen 4. A distance DA is a distance between the user 1(i.e., the virtual user position Uv) and the object OBJ. A distance DBis a distance between the user 1 (i.e., the real user position Ur) andthe screen 4.

The virtual camera VC images the object OBJ distant from the virtualuser position Uv by the distance DA to generate the virtual space imageIMG including the object OBJ. If the image of the object OBJ existingthe distance DA away is drawn as it is on the screen 4 existing thedistance DB away, the object OBJ appears to exist at a position adistance DA+DB away when viewed from the real user position Ur. As aninstance, let us consider a case where the distance DA is 10 m and thedistance DB is 2 m. When the image of the object OBJ existing 10 m awayis drawn as it is on the screen 4 existing 2 m away, that object OBJappears to exist 12 m away. That is, perspective in the real space SPris unnecessarily added in addition to perspective in the virtual spaceSPv. As a result, the object OBJ looks smaller than it originally is.This also causes the feeling of strangeness.

In view of the above, as the third feature, the virtual space imagingunit 130 cancels the perspective corresponding to the distance DBbetween the real user position Ur and the screen 4. More specifically,the virtual space imaging unit 130 adjusts a focal length of the virtualcamera VC towards telephoto side such that the perspective correspondingto the distance DB between the real user position Ur and the screen 4 iscancelled. As a result, the unnecessary perspective is cancelled, theoriginal sense of distance in the virtual space SPv is reproduced, andthus the user 1's feeling of strangeness is suppressed.

An adjustment amount of the focal length required for canceling theunnecessary perspective is determined based on the distance DB betweenthe real user position Ur and the screen 4. The position of the screen 4in the real space SPr is obtained from the screen information 230. Basedon the real user position Ur and the screen information 230, the virtualspace imaging unit 130 is able to determine the adjustment amount of thefocal length required for canceling the perspective corresponding to thedistance DB. It should be noted that the virtual space imaging unit 130performs the perspective adjustment for each screen 4.

4. Modification Example

As described above, a variety of processing is performed from theacquisition of the real user position Ur to the drawing of the virtualspace image IMG. Therefore, the virtual space image IMG drawn on thescreen 4 may be visually delayed by the processing time. In order tosuppress such the delay, the modification example makes a prediction(estimation) of the real user position Ur in the future.

FIG. 10 is a block diagram for explaining the modification example. Thedescription overlapping with the foregoing FIG. 4 will be omitted asappropriate. History information HST is information indicating a pasthistory of the real user position Ur and is stored in the memory device32.

In Step S110, the real user position acquisition unit 110 acquires thereal user position Ur. The real user position acquisition unit 110registers the acquired real user position Ur in the history informationHST to update the history information HST. Further, the real userposition acquisition unit 110 predicts (estimates) the real userposition Ur in the future based on the past history of the real userposition Ur indicated by the history information HST. For example, thereal user position acquisition unit 110 calculates an acceleration ofthe real user position Ur based on the past history of the real userposition Ur, and predicts the future real user position Ur from theacceleration. A Kalman filter or the like may be used for predicting thereal user position Ur.

In Step S120, the virtual user position acquisition unit 120 acquiresthe virtual user position Uv corresponding to the real user position Urin the future predicted in Step S110. In other words, the virtual userposition acquisition unit 120 acquires the virtual user position Uv inthe future. Then, in Step S130, the virtual space imaging unit 130places the virtual camera VC at the future virtual user position Uv toperform the virtual space imaging process.

As described above, according to the modification example, the real userposition Ur in the future is predicted, and the virtual space imagingprocessing is performed based on the virtual user position Uv in thefuture corresponding to the real user position Ur in the future. As aresult, the visual delay of the virtual space image IMG drawn on thescreen 4 is suppressed. This also contributes to the suppression of theuser 1's feeling of strangeness.

5. Summary

As described above, according to the present embodiment, the wearless VRsimulation is achieved. More specifically, the virtual camera VC isplaced at the virtual user position Uv corresponding to the real userposition Ur, and the virtual space image IMG is acquired by imaging thevirtual space SPv by using the virtual camera VC. The virtual spaceimage IMG is drawn on the screen 4 that is installed at a positiondistant from the user 1 and does not integrally move with the user 1.

Three types of processes, “fixation of vanishing point”, “lens shift”,and “perspective adjustment” have been described as ingenuities forsuppressing the feeling of strangeness when the virtual space image IMGis drawn on the screen 4 (see Section 3). The effect of suppressing theuser 1's feeling of strangeness can be at least obtained by at least oneof the three types of characteristic processes. Of course, two or moreof the three types of characteristic processes may be performed.

The wearless VR simulation according to the present embodiment does notdepend on the position, the orientation, and the shape of the screen 4.It is also possible to make a hexahedral VR experience room with aceiling, a floor, and front, rear, left, and right walls. It is alsopossible to further divide the screen 4 to realize a screenconfiguration with a more complicated shape. It is also possible to makea spherical VR experience room.

What is claimed is:
 1. A virtual reality simulator comprising: one ormore processors; and one or more memory devices storing virtual spaceconfiguration information indicating a configuration of a virtual space,wherein the one or more processors are configured to execute: a processof acquiring information on a real user position that is a position of ahead of a user in a real space; a process of acquiring information on avirtual user position that is a position in the virtual spacecorresponding to the real user position; an imaging process thatacquires a virtual space image by imaging the virtual space by using acamera placed at the virtual user position in the virtual space, basedon the virtual space configuration information; and a process ofprojecting or displaying the virtual space image on a screen that isinstalled at a position distant from the user in the real space and doesnot integrally move with the user, and the imaging process includes alens shift process that shifts a lens of the camera such that whole ofthe screen fits within a field of view of the camera.
 2. The virtualreality simulator according to claim 1, wherein the imaging processfurther includes a perspective adjustment process that adjusts a focallength of the camera such that perspective corresponding to a distancebetween the real user position and the screen is cancelled.
 3. Thevirtual reality simulator according to claim 1, wherein the one or moreprocessors are further configured to: predict the real user position infuture based on a past history of the real user position; and executethe imaging process based on the virtual user position in futurecorresponding to the real user position in future.
 4. A non-transitorycomputer-readable recording medium on which a virtual reality simulationprogram is recorded, the virtual reality simulation program beingconfigured to, when executed by a computer, cause the computer toexecute: a process of acquiring information on a real user position thatis a position of a head of a user in a real space; a process ofacquiring information on a virtual user position that is a position in avirtual space corresponding to the real user position; an imagingprocess that acquires a virtual space image by imaging the virtual spaceby using a camera placed at the virtual user position in the virtualspace, based on virtual space configuration information indicating aconfiguration of the virtual space; and a process of projecting ordisplaying the virtual space image on a screen that is installed at aposition distant from the user in the real space and does not integrallymove with the user, wherein the imaging process includes a lens shiftprocess that shifts a lens of the camera such that whole of the screenfits within a field of view of the camera.